An automobile gasoline pump is a device designed for uninterrupted supply of fuel to an installation in which the formation of a fuel mixture occurs. Even the slightest malfunction of it leads to interruptions in the engine, and with more serious malfunctions you simply will not start it.
In this article we will consider situations when the gasoline pump does not pump fuel at all, or pump, but not in the amount that the power unit needs for normal operation. We will also try to understand the possible causes of one or another malfunction of the fuel supply device and discuss methods for their independent elimination using the example of domestically produced automobiles VAZ-2109 and injector VAZ-2114.
What are gas pumps
Cars with gasoline engines, depending on the make, model and modification, can be equipped with different design gas pumps. But they are all divided into two main categories: mechanical and electrical. Most carburetor engines are equipped with mechanical fuel delivery devices. If you take the VAZ 2109 (carburetor), then from the factory it was equipped with a diaphragm pump manufactured by DAAZ. The main difference of this device is the simplicity of the design, which is easy to understand even for a beginner. In the carburetor "nine" gasoline pump is located in the engine compartment of a car. It is easy to recognize by the characteristic hemispherical hat and the fuel line hoses.
Engines injection VAZ 2114 are equipped with electric gas pumps. At the heart of their design is also a membrane, but unlike the “mechanics”, fuel supply devices in cars with automatic fuel injection are not under the hood, but directly in the tank.
Symptoms of a fuel pump malfunction
No matter what engine your vehicle is equipped with, the signs that something is wrong with the fuel delivery device are similar. These include:
- Lack of engine response to starting attempts.
- Violation of the stability of the power unit at idle.
- Friction.
- Power reduction.
Design of a petrol pump carburetor VAZ 2109
To understand why the VAZ 2109 petrol pump (carburetor) does not shake, let's briefly consider its design. So, the “nine” fuel supply device consists of:
- housing;
- a pusher with a mechanical swap lever;
- diaphragms assembly;
- caps with valves and fittings for attaching hoses;
- strainer;
- manual swap lever.
The principle of operation of a mechanical gasoline pump
The gas pump is driven by a camshaft cam that moves the plunger in the horizontal direction, forcing it to make reciprocating movements. The pusher, in turn, acts on the mechanical swap lever, and it already raises and lowers the rod of the membrane.
Thus, a certain pressure is created inside the fuel pump , which is maintained by the valves of the device cover. One of them lets the fuel inside, not letting it back in, and the second pushes it into the fuel line to the carburetor.
As you can see, the design is very simple, therefore, to determine the reason that the gas pump does not pump, it is enough to disassemble it and check the condition of the main elements.
Pusher
Since the body does not affect the operation of the gas pump in any way, if it is, of course, not damaged, then we will start with the pusher. This element is made of steel and just can not break. But to wear out - please, especially if it is not original, but purchased as a separate spare part. As its length decreases by a few millimeters, the gasoline pump does not pump fuel.
Rather, it shakes, but the amplitude of the movement of the diaphragm is significantly reduced. Hence the low fuel pressure in the system, and, as a consequence, interruptions in the engine. The standard pusher length for DAAZ pumps is 84 mm. Measure its length and replace the worn part if necessary.
Diaphragm
The most common diaphragm malfunction is its rupture. It also happens that it is deformed. Due to these damages, the diaphragm begins to pass fuel through itself, which also causes a drop in pressure in the system.
You can detect such a malfunction only by disassembling the fuel supply device. If the diaphragm is guilty of the fact that the gas pump does not pump, you will immediately see it. This problem is solved by replacing it.
Cover with valves and fittings
Since you disassembled the gas pump, do not be too lazy to check the valves. One of them should let in fuel, and another should let out. Just blow them and see how well they work. If the valves do not cope with their tasks, replace the cover assembly.
Pump Filter and Manual Pump Lever
The first thing you will see when disassembling the fuel supply device is a strainer. It is made of thin perforated plastic. The reason that the fuel pump does not pump can also be caused by its deformation or severe pollution.
In the first case, the filter must be replaced, in the second - rinse with liquid to clean the carburetors.
The manual pumping lever to the fact that the gasoline pump does not pump fuel when the camshaft rotates is irrelevant. The only thing that can break in it is a spring, which throws it back to its initial position.
Gas pump does not pump: injector
As already mentioned, pumps in carburetor and injection engines have a different design. In cars with forced fuel injection, all processes associated with its supply to the combustion chambers are controlled by an electronic control unit, therefore, damage to various kinds of electronic devices can occur here.
The main reasons for which the fuel pump of the injection engine does not shake include:
- malfunction of the electric drive of the device;
- clogged pump filter;
- failure of the relay;
- blown fuse.
How to understand that the cause of a malfunction in the engine is precisely the gas pump
Diagnosing problems with a gasoline pump in a car with an injection engine is much simpler than in a car with a carburetor engine. The fact is that when the ignition is turned on, the sound of the operation of the electric motor of the fuel module is clearly heard. It lasts a few seconds. This sound indicates that the fuel pump is turning, pumping fuel.
If this happens when you turn the key, it means that everything is in order with the device itself, and the reason must be sought elsewhere. Well, if if you turn on the ignition you don’t hear the characteristic sound of the pump, you can be sure that the problem is in it, or in the elements of its energy supply.
Start with a relay and fuse.
Given that the fuel supply module is located in the tank of the car, and it is not so easy to get to it, it is better to start the diagnosis with a relay and a fuse:
- Remove the screws that secure the mounting block cover to the left of the steering column.
- Under it, locate fuse F3 (15 A) and relay R2. These are the elements that we need to check.
- As for the fuse, it is necessary to “ring” the tester. If unsuitable - replace it.
It is quite difficult to check the relay in a garage. But you can take a similar (from a neighboring socket), obviously working relay, and put it instead of the diagnosed one. Now turn on the ignition. Is the gas pump pumping? Reason found! Well, if nothing has changed, move on.
Electric drive and filter
The fuel pump in the injector VAZ 2114 is an element of the fuel module, which is located in the tank of the car. It also includes:
- coarse filter;
- fuel level sensor;
- nozzles for connection to the fuel line.
To get to the module, you must remove the lower part of the rear seat, disconnect the wiring harness and unscrew the 8 screws securing its cover. Remove the entire device assembly. First of all, inspect the coarse filter. If it is clogged, replace it.
To check the motor, you will need to connect it directly to the battery terminals. In the case of its normal operation, “ring” the wiring and check the contact of the ground wire on the module cover. If the electric motor does not show signs of life, the question "why does not the gas pump pump" finally found its solution.
Trying to repair it yourself is impractical. Just buy a new motor and install instead of the old one. And yet, you should not spend money on the purchase of the entire module, which now costs about 3 thousand rubles. Buy an electric motor and a new filter separately. All this will cost you three times cheaper.